A heat engine in which; by causing a warm field and a cold field to act alternately on an incompressible substance which undergoes volumetric variation due to temperature variation, alternating volumetric variation is caused to occur in the incompressible substance; this volumetric variation is changed into a linear displacement of an output displacement member; and rotational motion is taken out (derived) from this by way of a motion-conversion mechanism is publicly known as the present applicant has previously proposed (reference being made to U.S. Pat. No. 4,222,239 of Sept. 16, 1980.
In this known heat engine, a liquid or a solid, for example a paraffinic substance, is used as the above mentioned incompressible substance, and, in order to derive the volumetric variation of this incompressible substance as a mechanical displacement, and output displacement member is provided in direct contact with the incompressible substance, or another displacement transmitting medium is interposed between the incompressible substance and the output displacement member. The provision of the output displacement member in direct contact with the incompressible substance is desirable because that the volumetric variation of the incompressible substance can be changed directly into displacement of the output displacement member. However, in this case, in order to cause a warm field and a cold field to act alternately on the incompressible substance, a piston which undergoes displacement while dividing the warm field and the cold field is necessary, and a complicated mechanism is required for driving this piston. On the other hand, in the above mentioned latter case wherein another displacement transmitting medium is interposed between the incompressible substance and the output displacement member, a sealing member for separating the incompressible substance itself from the above mentioned medium is necessary, and, moreover, it is necessary to cause the incompressible substance to move alternately between the warm field and the cold field while sealing it with the sealing member, for which a complicated mechanism similarly becomes necessary.
This invention has an object of making the heat engine of the above described type, which is mechanically complicated and is relatively wasteful, more compact both mechanically ans spatially for making it into an engine which is suitable for practical use.